Process and apparatus for solids conveyance in the conversion of hydrocarbons



@y EL w55 C. H. O. BERG PROCESS AND APPARATUS F'OR SOLIDS CONVEYANCE INTHE CONVERSION OF HYDROCARBONS Filed May 27, 195o 62m; A( a man UniteStates Patent 0 PRCESS AND APPARATUS FR SLIDS CON- VEYANCE IN THECNVERSION 0F HYDRO- CARBONS Clyde H. (l. Berg, Long Beach, Calif.,assigner to Union Oil Company of California, Los Angeles, Calif., a corporation of California Application May 27, 1950, Serial No. 164,837

27 Claims. (Cl. 19-52) This invention relates to improvements inoperations involving the contacting of gases or vapors with movingsolids. More particularly this invention relates to an improved processand apparatus for the continuous contacting of gases and vapors with asubstantially compact moving bed of catalyst or other solids forcarrying out chemical reactions. Specifically this invention involves animproved method and apparatus for conveying solids employed in movingbed operations in which the solids are conveyed in substantially compactform under the influence of a concurrently flowing and depressuringconveyance iiuid as hereinafter more fully described. i

Operations employing moving beds of substantially compact solids, suchas catalysts for chemical reactions, are well known in the art andperhaps the most publicized example is the T. C. C. process forcatalytic cracking of hydrocarbons. In this process a regenerator and areactor are employed in separate vessels, the catalyst being passed insubstantially compact form downwardly by gravity through each vessel. Apair of bucket elevators are used to raise the catalyst from the bottomof each vessel for introduction into the top of the other. Whileelevators of this type are efcient from an energy requirementstandpoint, they are somewhat difficult to maintain at the operatingtemperatures of from 800 F. to llOO" F. and considerable grinding ofsolids to nes is experienced.

The primary object of the present invention is to provide an improvedprocess and apparatus for carrying out operations involving the contactof gases or vapors with granular solids either in substantially compactform or where uidized particles of catalyst, oil shale, coke, tar sandand the like are treated at elevated temperatures or where solidparticles are merely heat treated such as in lime burning.

A further object of this invention is to provide an improved process andapparatus for the contacting of gaseous or vaporous reactants with asubstantially compact moving bed of granular catalyst.

Another object of this invention is to provide `in operations involvingmoving beds of solids an improved method and apparatus for conveyingthese solids in the absence of elevators or other moving mechanicaldevices from the bottom ot a vessel to the top of the same or ditierentvessel substantially without abrasion or attrition loss.

A more specific object of the present invention is to provide in movingbed operations an improved method for conveying such solids insubstantially compact form upwardly through lift lines from the bottomto the top of the same or a different vessel in the presence of aconcurrent tlow of depressuring lift gas.

An additional object of the present invention is to provide a processand apparatus having the aforesaid improved solids conveyance operationin the refining of fractions of crude petroleum wherein said fractionsare contacted at reaction temperature and pressure conditions with asubstantially compact moving bed of solids such as a catalyst in suchpetroleum refining operations ice as cracking, coking, hydroforming, anddesulfurization as well as others.

It is a further object of the present invention to provide animprovement in the process and apparatus for the conveyance of granularsolids in which the energy re quired is considerably reduced.

It is an additional object of the present invention to provide acontinuous solids-fluids contacting process including a solidsregeneration step in which the granular solids are recirculated throughconveyance conduits in substantially compact form by means of arecycling stream of depressuring conveyance fluid.

Other objects and advantages of the present invention will becomeapparent to those skilled in the art as the description and illustrationthereof proceeds.

Brieily, the presentrinvention comprises a method and apparatus in whicha continuous downward flow of granular solids in substantially compactform is maintained through a vessel or Vessels and through which gaseousor vaporous constituents are passed in direct contact with the solidsfor chemical conversion or reaction. The granular solids collecting inthe bottom of the vessel are removed therefrom and are then transferredupwardly in substantially compact form through a lift line or conduit tothe top of the same or a dierent vessel for passage downwardlytherethrough in substantially compact form. The upward flow of solidsthrough the lift lines is effected by a `concurrent flow of depressuringlift fluid, the frictional forces of which, acting against the granularsolids by flowing through the interstices thereof, are sufficient tocounteract the forces of gravitation and friction of moving solidsagainst .the walls of the conduit. The depressurng fluid generates apressure drop per unit length of conduit suflicient to overcome thegravitational force in the opposite direction (ps cos 0) wherein ps isthe bulli density and 0 is the angular deviation of the conveyance linefrom the vertical. The ratio of the former to the latter,

da li p8 00.50

loperation is that the moving solids are in substantially compact formthroughout the entire conduit through i which they flow completelypreventing the impact of the lll solids particles against otherparticles or conduit surfaces which is one of the principal causes ofsolids loss by attrition.

In most moving bed operations involving the use of solids such ascatalysts, at least two individual operations or reactions are eiected;namely, the reaction step and regeneration step. ln the former, thecatalyst is contacted with reactants to form products and a spentcatalyst, and in the latter step the spent catalyst is contacted withsome form of a regeneration fluid to form a spent regeneration fluid andregenerated solids which are returned to the rst step. Often thefluidsemployed in the regeneration step are not compatable with the fluidsbeing treated in the `reaction step and care must always be taken toinsure that no mixing of these fluids occurs. This is 3 v particularlytrue in catalytic hydrocarbon cracking operations in which the iiuid inthe reaction step is gas oil or naphtha vapor and the iiuid in theregeneration step is a mixture of air and flue gas.

Another characteristic of the present invention involves the combinationof pressuring chambers by means of which the granular solids aretransferred from the bottom of the contacting vessels and introducedinto the conveyance conduit or litt line for conveyance to the top ofthe other contacting vessel. An additional characteristic of the presentinvention lies in the removal of a portion of the conveyance iiuid frompoints along the length of the line thereby reducing the velocity of theconveyance fluid therein and returning this gas to an interstage inletof the muitistage conveyance fluid compressor. By a combination or thearrangement of the pressuring chambers and the removal of conveyanceiluid from the conveyance conduit it has been found that a considerableincrease in the quantity of solids transported may be realized for thesame expenditure of energy previously required.

ln a solids contacting process in which one vessel comprises a reactorand a second vessel comprises a spent solids regenerator, the granularsolids are conveyed through the operational steps above described. Aninduction chamber is maintained at the inlet of each convoyance conduit.Each of these induction chambers is operated at a. substantiallyconstant pressure and discharges a substantially continuous stream ofgranular solids into the conveyance conduit. Granular solids removedfrom the reactor for example are introduced into a surge chambermaintained constant at the reactor pressure. The surge chambercommunicates with a pressuring chamber which in turn communicates withthe induction chamber. The pressuring chamber is lirst depressured tothe reactor pressure and iilled with granular solids from the surgechamber. Subsequently it is isolated from the surge chamber, pressuredto the induction chamber pressure, and the granular solids are passedfrom the pressuring chamber into the induction chamber. The inductionchamber is provided with a relatively large surge volume so as tomaintain a continuous output of granular solids into the conveyanceconduits.

In a system involving two or more parallel solidsfluid contactingvessels, each vessel is provided at its lower granular solids outletwith a surge chamber and a pressuring chamber which are operated inalternation so as to provide a substantially continuous discharge ofgranular solids from the pressuring chambers into a single inductionchamber or the plurality of contacting vessels may discharge into asingle surge vessel if desired and a minimum of two pressuring chambersmay be used to transfer solids therefrom into the induction chamber.

ln a system involving a single reactor or other solidsfluid Contactvessel a single surge chamber is provided which feeds granular solidsinto a pair of pressuring chambers operated in alternation to provide asubstantially constant granular solids flow into the induction chamberwhich feeds into the conveyance conduit for transporting granular solidsremoved from such a vessel.

One characteristic of the present invention lies in the depressuring ofa pressuring chamber at the induction chamber pressure into anotherpressuring chamber at the surge chamber pressure. in such a step anequilibrium pressure intermediate between the` surge chamber pressureand the induction chamber pressure will result materially reducing thequantity of high pressure fluid rcquired in pressuring the pressuringchambers up to the induction chamber pressures.

The process and apparatus of the present invention is more easilydescribed and understood in connection with the accompanying drawingwhich illustratev schematically a catalytic cracking process involving amoving bed of solid granular catalyst and in which a pair of reactorsare operated in parallel. A single catalyst regenerator is employed totreat the spent catalyst discharged from the reactors. it is ofimportance to note that the pressuring system for handling granularsolids at the bottom of the reactors is the saine in principle to thatemployed at the bottom of the regenerator, the granular solids passingfirst into a surge chamber operating at the same pressure as the vesselsfrom which the solids were removed, the solids then passing intopressuring chambers which are alternately pressured and depressured toand from the pressures of the induction chamber and the surge chamberrespectively. If parallel regenerators were employed, the same surge andpressuring chamber scheme is used as is used in handling granular solidsfrom the reactors. In the case of using a single reactor a solidshandling scheme of surge and pressuring chambers would be used as isshown at thc bottom of the regenerator.

in the drawing, the apparatus of the present invention is provided withreactors l0 and 12 provided with granular solids inlets M- and 16respectively, introducing granularcatalyst solids from regeneratedcatalyst hopper 18. The granular catalyst passes downwardly through thereactors as a substantially compact moving bed of soiids to be directlycontacted by hydrocarbon fluids to be reacted or converted. inlets 20and 22 are provided for the introduction of such fluids and outlets 24and 26 are provided for the removal of reaction or conversion productsin a concurrent type of contacting operation. For counter-current iiowthe reactants may be introduced via lines 24 and 26 and the productsremoved via lines 20 and 22.

The apparatus employed for transferring granular solids from thereactors is typical of the conveyance means in this invention as appliedto the removal and conveyance of solids from two or more vessels. ifdesired a single surge chamber may be employed With inlets from theplurality of reactors and outlets into two or more pressuring chambers.A single pressuring chamber may be used but is not preferred since thesurge volume of the induction chamber increases as does the powerrequired for pressuring and deprcssuring.

The granular solids passing through reactors 10 and 12 liow at a rategoverned by control valves 28 and 30 respectively, the granular solidspassing via transfer lines 32 and 34 into surge chambers 36 and 38,respectively. Yhese surge chambers are maintained constantly atsubstantially the same operating pressure as reactors il) and i2 thusinsuring a continuous ow of solids from the reactors to the lrespectivesurge chambers. From the surge chambers, alternately, granular solidsare withdrawn and passed to their respective pressure chambers 40 and 42by means of transfer lines 44 and 46 controlled by automatic cyclevaives 48 and 56, respectively. Pressure chambers d@ and 42 are providedrespectively with transfer lines 52 and Se controlled by automatic cyclevalves 56 and SS and by means of which solids are charged into reactorinduction zone dii. Thus, when pressuring chamber i0 is dcpressured tothe reactor pressure, chamber 42 is pressured to the same pressure asinduction chamber 6i?. in this part of the cycle, pressuring charn- 4@is being iilled from surge chamber 36 and pressuring chamber 42 is beingemptied via transfer line 54 into induction chamber 60. When pressuringchamber 4i) is iilled and chamber 42 is emptied of catalyst, valves 43and 53 are closed and the high pressure iiuids in pressuring chamber 42are partiy depressured via line 62 controlled by automatic cycle valve64 into pressuring vessel i0 bringing the pressure of the two Vessels tosome intermediate equilibrium pressure. Jalve 64 is then closedisolating the two pressuring vessels. Pressuring chamber d2 is thenfurther depressured from the intermediate equilibrium pressure to thereactor pressure via line 66 controlled by cycle valve 68 by dischargingfluids into low pressure manifold 7i). At the same time pressuringvessel et? is pressured from the intermediate pressure to the reactorinduction chamber pressure by introducing high grosera pressure fluidsvia line 72 controlled by cycle valve 74 from high pressure fluidmanifold '76. At this point valves 56 and 50 are opened and granularsolids from pressuring chamber flow via transfer line 52 into reactorinduction chamber 60 while granular solids ow from surge chamber 38 viatransfer line 46 into pressuring chamber 42. When pressuring chamber 4@is emptied and pressuring chamber 42 is filled, valves 5b and 56 areclosed, valve 64 is reopened, the high pressure fluids present inpressuring chamber 4t) depressure into pressuring chamber'42 via line 62establishing the intermediate equilibrium pressure as before. Valve 64is then closed, pressuring chamber 4t) is depressured to low pressuremanifold 70 by means of line 78 controlled by cycle valve 80 andpressuring vessel 42 is pressured from high pressure manifold 76 vialine 'ft2 controlled by cycle valve 34. Cycle valves 48, 5b, 56, 58, 64,6%, 74, 80, and 84 are automatically operated in a predetermined timecycle to repeat the operation of pressuring and depressuring, fillingand emptying of pressuring chambers 40 and 42 described.

A continuous granular solids flow empties into surge chambers 36 and 33.Because of their surge capacity an intermittent removal of granularsolids therefrom into the respective pressuring chambers docs notdisturb the uniformity of granular solids flow through the reactorsproper. Because of the surge capacity of the reactor induction chamber60, the substantially constant llow of granular solids therefrom is notdisturbed by the intermittent introduction of granular solids frompressuring chambers 40 and 42. Therefore, by supplying reactor inductionchamber 6i) with a supply of high pressure conveyance fluid via line 86controlled by valve 38 from high pressure manifold 76 a substantiallyconstant flow of compact granular' solids from induction chamber 60 ismaintained by gravity into the conveyance zone and under the influenceof depressuring conveyance tluid through the lower or primary section 90of the spent solids conveyance conduit. A similar solids flow takesplace in the regenerated solids conveyance conduit.

The conveyance conduit consists essentially of a lower or primarysection 90 and an upper or secondary section 91. The two sections areseparated by a conveyance tluid disengaging chamber 12. Granular solidsare discharged into disengaging chamber 92 and a portion of theconveyance fluid entering with the granular solids is removed fromdisengaging tray 94 via line 96 at a rate controlled by valve 993. inthis manner the quantity and consequently the velocity of the conveyancetiuid flowing through the conveyance conduit at this point is reducedthereby decreasing the required cross sectional area of f thc secondarysection of the spent solids conveyance conduit. The granular solids passdownwardly through disengaging tray 94, passing from the lower openingof disengaging chamber 92, and are conveyed through upper section 91 ofthe conveyance conduit under the influence of the depressuring remainingportion of conveyance fluid into spent solids separating chamber 101i. Arestrictive force is applied by means 1tt2 whereby the granular solidsin the conveyance conduit are maintained in substantially compact forni.The conveyance fluid discharging from the conveyance conduit with thegranular solids is removed from separator chamber 1li@ via line 1&4controlled by valve 1116 which may comprise a back pressure regulator ora flow recorder controller. The spent granular solids thus conveyed passfrom separator chamber via transp fer line 1418 at a rate controlled byvalve into regenerator 112. The granular solids pass downwardlytherethrough in substantially compact form and are contacted directlywith an oxygen-containing gas for regeneration of the spent solids (inthe case of hydrocarbon conversion example may be provided inregenerator 112 for the dissipation of the exothermic heat releasedduring regeneration. The regenerated granular solids thus formed areremoved via transfer line 118 at a rate controlled by valve 12b and aretreated as subsequently described for conveyance to regenerated solidshopper 18. p

The system for handling the regenerated granular solids is typical ofthe apparatus of this invention for removing granular solids from asingle column and introducing it into the conveyance conduit. Itconsists of surge chamber 122, pressuring chambers 124 and 126, andregenerated solids induction chamber 12S. 1n alternation pressuringchambers 124 and 126 are pressured and depressured to and from thepressure of regenerator induction chamber 12b and the pressure ofregenerator 112. The surge chamber 122 is operated at the same pressureas that of the regenerator. While pressuring chamber .124 is depressuredand pressuring chamber 126 is pressured, granular solids pass from surgechamber 122 via transfer line 130 controlled by cycle Valve 132 intopressuring chamber 124 while granular solids pass from pressuringchamber 126 via transfer line 134- controlled by cycle valve 136 intoregenerated solids induction chamber 128. When pressuring chamber' 124is full and chamber 126 is empty, cycle valves 132 and 136 are closed.The high pressure fluids present in chamber 126 are then depressuredinto chamber 124 via line 138 con trolled by cycle valve 140 bringingthe two chambers to an intermediate pressure at equilibrium. Cycle valve140 is then closed and chamber 126 is depressured to the regeneratorpressure via line 142 controlled by cycle valve 144 while chamber 124 ispressured to the pressure of regenerated solids induction chamber 128 bymeans of high pressure gas flowing viafline 146 controlled by cyclevalve 14S from high pressure iiuid manifold 76. Subsequently cyclevalves 150 and 152 are opened so that granular solids pass via transferline 154 from pressuring chamber 124 to induction chamber 128 and viatransfer line 156 from surge chamber 122 to pressuring chamber 126. Whenchamber 124 is emptied and chamber 126 is full, cycle valves 152 and 150are closed, and the high pressure fluids in pressuring chamber 124 aredepressured via line 138 bringing pressuring chambers v 124 and 126 toan intermediate equilibrium pressure.

processes) or with other regeneration or heating fluids."

These uids thus introduced enter via inlet 114 and leave via outlet 116in concurrent flow or the inlets and outlets may be reversed forcountercurrent flow. lf required means not shown comprising steamgenerating coils fori Pressuring chamber 124 is further depressed vialine 158 controlled by cycle valve 160 into low pressure manifold 70while pressuring chamber 126 is pressured to the pressure of inductionchamber 12S via line 162 controlled by cycle valve 164. Again, as in thesystem for handling the spent granular solids, the cycle valves areoperated automatically on a time cycle to permit the introduction ofgranular solids from surge chamber 122 alternately into pressuringchambers 124 and 126 and from these last-named chambers alternately intoregenerated solids induction chamber 128. Because of the surge capacityof surge chamber 122 the alternate removal of solids therefrom does noteffect the flow rate of granular solids in the `regenerator and becauseof the surge volume in induction chamber 123 the alternate introductionof granular solids thereinto from pressuring chamber 124 and 126 doesnot effect the constant discharge of granular' solids from the inductionchamber.

Regenerated solids induction chamber 128 is provided with a continuoussupply of fluids from high pressure fluid manifold '76 via line 166controlled by valve 168.

The conveyance tiuid thus introduced is depressured concurrently with acontinuous flow of substantially compact granular solids from inductionchamber 12S through the regenerated solids conveyance conduit consistingof lower or primary section 17d and upper or secondary section 171.These two sections are separated by conveyance uid disengaging chamber172. Disengaging chamber 172 is provided with a transverse disengagingtray 174 from which a portion of the conveyance Huid is removed via line176 at a rate controlled by valve 173. The con voyance fluid thusremoved may be combined with that removed from disengaging chamber 92previously described. The gases thus removed will be discussed below.

The granular solids being depressured in substantially compact formthrough upper section 171 of the regenerated solids conveyance conduitdischarge into solids hopper lt. A restrictive `force to the dischargingsolids is provided by means lltl whereby the granular solids in theconveyance conduit are maintained in substantially compact form. Theconveyance iiuids are disengaged in hopper 1S from the dischargedgranular solids and are removed frorn the hopper via line 182 controlledby valve 84. Within hopper ls the granular solids are divided, in thepresent illustration, into two streams passing respectively intoreactors and l2 via lines 14 and 16 at rates controlled by valves and17. The solids then recirculate through the reactors as described above.

Returning now to the conveyance fluids disengaged from disengagingchambers 92 and 172, these fluids are joined in manifold 5.86 and passthrough cooler and dust remover 1553. Since in most catalytic andthermal processes the granular' solids conveyed are at a temperature ofthe order of 800 i". to .1100 F., the conveyance fluid thus removed isat substantially the same temperature. Furthermore, a certain amount odust is generated which is picked up by the gas streams disengaged fromdirect contact with the solids. The gas thus disengaged from thedisengaging chambers 92 and 1172 therefore is cooled and filtered by anyone of a number of means to provide a cool dust-free conveyance fluid ata pressure intermediate between that of the induction chambers el) and128 and the pressures of hopper i8 and separator chamber 10i). The thustreated conveyance fluid subsequently passes via line 19o into aninterstage of multi-stage conveyance iiuid compressor 1192.' This gas isjoined by conveyance tluid introduced via line 194 into the first stageof compressor' 192 and the total is compressed ultimately to a pressuresomewhat `greater than that of high pressure manifold '76. The highpressure gas is conveyed via line H6 into high pressure conveyance fluidsurge chamber 198. The surge chamber provides a source of high pressureiuid to place a more or less uniform load on cornpr'essor 1&2 since thedemands of high pressure iluid in the process are not quite uniform.High pressure fluid is introduced into high pressure manifold 76 vialine 200.

Gas is removed from the low pressure manifold 7l! by means oi line 202and is usually discarded and vented to the atmosphere. lt may however,be recycled in aeeordance with a modification of: the present inventiondescribed subsequently.

Example The principles of the present invention were applied to acatalytic cracking process involving two systems each of which issimilar to the apparatus outlined in the drawing. A catalyst circulationof 500 tons per hour of synthetic bead cracking catalyst was maintainedin each system. The catalyst granules had a bull; density of pounds percubic foot. The reactor surge chambers opcrate at a pressure of 25pounds per square inch absolute and had a volume of 239 cubic feet each.The reactor pressuringI chambers each had a volume of 159 cubic feet.The reactor induction chamber had a volume of 599 cubic feet andoperated at a pressure of 95 pounds per square inch absolute.

The regenerator operated at a pressure of 16.2 pounds per square inchabsolute. The rcgcnerator surge chamber had a volume of 500 cubic leetand operated at a pressure of 16.2 pounds per square inch absolute. Theregenerator pressuring chambers had a volume of 159 cubic feet each andwere operated in pressure between the limits of 16.2 and 95 pounds persquare inch absolute. The regenerator induction chamber had a volume ofG cubic feet and was operated at 95 pounds per square inch absolute. Theprimary and secondary sections of both the spent solids conveyanceconduit and the regenerated solids conveyauce conduits were tapered,increasing in diameter from a minimum or' l2 inches at the inlet to amaximum ot 21.3 inches at the outlets of each or" the four sections inorder to maintain the conveyance force ratio at a substantially constantvalue throughout the length oi the conduits. The conveyance iiuiddisengaging chambers were vessels having a maximum diameter of 4 feetand the chamber was constructed with an upper 45 cone and a lower 60cone with a lower l-foot base coinciding. The energy required to conveythe 50i) tons per hour circulation of granular solids was 364 adiabatichorsepower. The conveyance luid employed was air, being introduced intothe inlet of the first stage of the cornpressor at a pressure of r4.7pounds per square inch absolute and at a rate of 1949 standard cubicfeet per minute. ln the first stage of the compressor this air wascompressed to an iuterstage pressure of 41.2 pounds per square inchabsolute and was joined with 828 standard cubic feet per minute ofconveyance iluid removed from lift line disengaging chambers. ln thesecond stage of the compressor, the combined stream of 2777 standardcubic feet per minute of air is compressed to a pressure of pounds persquare inch absolute and introduced into the high pressure liuidmanifold. ln operation, the intermediate pressure at equilibrium in thereactor pressuring chambers was 66.7 pounds per square inch absolute andthe equilibrium pressure in the regenerator pressuring chambers was 63.3pounds per square inch absolute.

The foregoing process is employed to catalytically crack 15,000 barrelsper day of straight run and cracked gas oil at a temperature of 335 F.with a catalyst-to-oil Weight ratio yot 5.16. The horsepower requirementfor the conveyance of granular solids according to this invention is 24%of that required for conveyance of the solids a suspension in a gas liftprocess and considerably less than that required for conveyance of thesolids with bucket elevators. The attrition rate of the granular solidsin the process of the present invention is also Well below thatencountered with either the gas suspension lift or bucket elevator typeconveyauces.

With reference to the drawing, the 'foregoing example involves anoperation in which the separator chamber above the regeneration vesseland the catalyst hopper above the reactors were operated at 1.5 poundsper square inch gauge pressure. Since the reactors were operated atabout 24.7 pounds per square inch absolute, transfer lines i4 and 16were actually sealing legs 16 inches in diameter and 81) feet in length.The conveyance duid discharged from separator illil and hopper 13 wasvented to the at mosphere.

A desirable modicatiou of the present invention lies in operating hopperl@ at substantially the same pressure as that of reactors lil and l2,namely 24.7 pounds per square inch absolute. By so doing the lengthysealing legs 214 and .lo may be eliminated and the granular catalystintroduced directly f rom hopper 1S into the reactors. The conveyancefluid removed from hopper 1?: at a pressure of 24.7 pounds per squareinch absolute may be introduced into the low pressure stage ofcompressor i9?, further decreasing the horsepower requirements. The lowpressure fluid from reactor pressuring chambers 40 and 42 is alsodischarged at the same pressure and may be combined with the conveyancetluid from hopper 18. These off gases must of course be cooled andfiltered to remove dust particles before recompression.

Another desirable modification of the present invention is theincorporation in separator E92 and/or hopper with provision forelutriating granular solids lines from the circulating stream of solids.Thus, means 18D and lili may comprise cylindrical chambers of crosssectional area greater than that of said conveyance conduit and throughwhich the granular solids pass in countercurrent Contact to all or aportion of the conveyance fluid thereby' suspending the solids lines andremoving them from the system. The incorporation in the process ofartiest/s il such elutriation apparatus decreases the pressure drop offluids passing through the regenerator and the reactors, increases theuniformity of catalyst contact `with the fluids, and materially reducesthe fluid by-passing effect known as channelling in the granular solidsbed.

In another desirable modification of the present invention and which isparticularly applicable to contacting processes in which a relativelylarge quantity of hydro carbonaceous material is deposited on thegranular solids, the conveyance fluid preferably comprises a relativelyoxygenfree flue gas which may be recycled in the process or generated,compressed and depressured through the conveyance conduit and pressuringchamber' described. ln the example above, the catalystdoeoil ratio wassufficiently high that the quantity of carbon laid down on the catalystduring the cracking operation was insufficient upon complete combustionin air to raise the temperature of the catalyst above the deactivationtemperature. For such a situation fresh air is the most convenientconveyance liuid.

ln some installations steam may be employed as the conveyance [luid butcare must be taken to avoid use of this gas with catalysis which aresteam deactivated. The compressed hydrocarbon gases such as methane,ethane, and the like, or natural gas, or cracked dry gases may also beemployed as conveyance fiuids. it is to be noted that in processesinvolving liquid Contact with granular' solids, a liquid conveyancefluid may be substituted and a conveyance conduit having constant crosssectional areas may be used. Liquid conveyance fluids may also be usedwith processes wherein vaporous fluids are contacted with solids.

lt is to be understood that the present invention is not to be limitedto the cracking process described above by way of illustration and thatthe novelty lies in the conveyance step of the operation and thecombination of the pressuring and depressuring chambers with theconveyance conduits through which a depressuring conveyance fluidconveys compact grantuar solids as a continuous moving mass and from anintermediate point in which a portion of the conveyance fluid iswithdrawn and returned to an intermediate stage of the conveyance fluidcompressor.

Therefore, the conveyance process and apparatus of the present inventionmay be combined with virtually any other process involving a moving orrecirculatory stream of granular solids.

A particular embodiment of the present invention has been hereinabovedescribed in considerable detail by way of illustration. it should beunderstood that various other modifications and adaptations thereof maybe made by those skilled in this particular art without departing fromthe spirit and scope of this invention as set `forth in the appendedclaims.

i claim:

l. A process for recirculating granular solids successively through afirst and a second fluid contacting zone which comprises passinggranular solids from said first contacting zone successively through afirst surge zone, alternately into a plurality of first pressuringZones, introducing a relatively uniformi flow of granular solids fromsaid plurality of pressuring zones into a first induction zone,introducing a conveyance fluid into said induction zone, depressuringsaid conveyance uid concurrently with said granular' solids from saidfirst induction zone through a first conveyance zone to a secondseparator zone, maintaining said granular solids in said conveyance zonein substantially compact form, flowing said granular solids from saidsecond separator Zone into said second contacting zone, flowing granularsolids from said second contacting zone successively through a secondsurge zone and alternately into a plurality of second pressuring zones,passing said solids from said pressuring zones into a second inductionZone, introducing a conveyance fluid into said second induction zone,depressuring said conveyance fluid from said second induction zonethrough a second iii conveyance zone into a first separator zone,maintaining said granular solids in said second conveyance Zone insubstantially compact form and as a continuously moving mass, flowinggranular solids from said first separator zone into said firstcontacting zone, withdrawing at least a portion of said conveyance fluidfrom eac-h of said first and second conveyance Zones at an intermediatepoint therein, combining the fiuid thus formed, repressuring said fluid,and introducing at least a portion thereof into said first and secondinduction Zones.

2. A process according to claim l wherein said first contacting zonecomprises a plurality of reaction zones, introducing granular solidsinto each of said plurality ot reaction zones, passing solids from eachof said plurality of reaction zones in succession through a surge zoneand a pressuring zone, and from each of said pressuring Zones into saidfirst induction zone.

3. A process according to claim l wherein said first contacting Zonecomprises two elongated reaction Zones, wherein said granular solidscomprise a solid granular' cracking catalyst, wherein said secondcontacting zone comprises a catalyst regeneration zone, introducing aseparate stream of regenerated granular catalyst into each of saidreaction zones, conveying by means of said first conveyance zone astream of spent hydrocarbonaceous cracking catalyst into saidregeneration zone, regenerating said spent catalyst in said regenerationzone by contacting the same with an oxygen-containing gas forming aregenerated catalyst, conveying said regenerated catalyst by means ofsaid second conveyance zone to said rst separator zone, maintaining saidregenerated cracking catalyst at cracking conditions of pressure andtemperature within said reaction zone, and contacting said catalysttherein with a hydrocarbon oil to be cracked.

4. A process according to claim l including the steps of operating eachof said surge zones at a relatively low pressure, maintaining asubstantially constant ow rate of granular solids from each of saidreaction zones into the surge zone communicating therewith, maintainingsaid first induction zone at a relatively high pressure, anddepressuring one of said pressuring zones while pressuring another ofsaid pressuring Zones by flowing fluids therebetween bringing both to anintermediate pressure.

5. A process according `to claim l including the step of elutriatingsolid granular fines `in at least one of said separating chambers,removing a conveyance fluid containing suspended solids fines therefrom,and flowing fines-tree granular solids from said separator zone to thecontacting zone communicating therewith.

6. A process according to claim l in combination with the steps ofestablishing a conveyance fluid disengaging zone at an intermediatepoint along each of said first and second conveyance zones, decreasingthe conveyance tiuid velocity to a relatively low value therein,removing a portion of said conveyance fluid from each of saiddisengaging zones substantially at the points therein of lowestvelocity, and depressuring the remainder of said conveyance fluidthrough the remaining portion of each of said conveyance zones whilemaintaining the granular solids therein in substantially compact form.

7. A process according to claim l including the step of flowing saidgranular solids from said first and second induction zones by gravityinto said conveyance zone and subsequently conveying said solids throughsaid convoyance zone in substantially compact form under the influenceof a depressuring conveyance fluid owing at a sufficient rate toestablish a conveyance force ratio having a value greater than 1.0.

8. A process according to claim 7 in combination with maintaining saidconveyance force ratio at a substantially constant value throughout saidconveyance zones.

9. A process for the conveyance of granular solids which comprisespassing said granular solids from a surge zone into a pressuring Zone ata relatively low pressure, raising the pressure of the latter zone to arelatively high aroaevs pressure, flowing the granular solids into aninduction zone, introducing thereinto a conveyance fluid at a highpressure relative to that at which solids are discharged afterconveyance, depressuring said conveyance iiuid concurrently with asubstantially compact nonfiuidized mass of granular solids from saidinduction zone through a primary conveyance zone into a disengagingzone, removing a part of said conveyance fiuid from said disengagingzone, depressuring said granular solids in substantially compact formfrom said disengaging zone through a secondary conveyance Zone with theremainder of said con- Vveyance fluid, discharging granular solids andconveyance fluid from said secondary conveyance Zone, and applying arestrictive force against solids discharging from said conveyance zonesthereby maintaining the solids moving through said primary and secondaryconveyance zones as a continuous compact nonfiuidized porous moving massof granular solids having substantially the same bull: density as adownwardly moving bed of said solids,

l0. A process for the conveyance of granular solids which comprisesestablishing a first surge zone communicating with a first pressuringzone and a second surge zone communicating with a second pressuringzone, said first and second pressuring zones communicating with aninduction Zone, flowing granular solids as a downwardly moving bed fromsaid first surge Zone to said first pressuring zone at a relatively lowpressure, fiowing granular solids as a downwardly moving bed from saidsecond pressuring zone to said induction zone at a relatively highpressure, subsequently depressuring said second pressuring zone to thesame pressure as said second surge zone, pressuring said firstpressuring Zone to the pressure of said induction zone, fiowing granularsolids as a downwardly moving bed from said second surge zone to saidsecond pressuring Zone, owing solids as a downwardly moving bed fromsaid first pressuring Zone to said induction zone, introducing aconveyance fiuid into said induction Zone, depressuring said conveyancefluid concurrently with a compact nonfluidized mass of granular solidsthrough a conveyance zone communicating therewith, and applying arestrictive force against solids discharging from said conveyance zonethereby maintaining said granular solids in substantially compactnoniiuidized form in said conveyance zone at a bulk densitysubstantially the same as that of said downwardly moving beds of compactnonfluidized solids.

l1. A process according to claim l0 wherein a substantially continuousfiow of granular solids is maintained into said rst and second surgezones.

l2. A process according to claim l() wherein one of said pressuringzones is depressured from a relatively high pressure to an intermediatepressure by placing said pressuring zone in communication with saidsecond pressuring zone prior to pressuring said second pressuring zoneto the pressure of said induction Zone and depressuring the other ofsaid pressuring zones to pressure its communicant surge zone.

13. A process according to claim l0 wherein a substantially constanttiow rate of solids is maintained from said induction zone through saidconveyance Zone.

14. A process according to claim l0 wherein said first and secondpressuring zones are alternately pressured and depressured to effect arelatively uniform rate of solids introduction into said induction zone.

15. A process according to claim l() wherein a portion of saidconveyance fiuid is removed from an intermediate point in saidconveyance conduit, is compressed, and at least part is reintroducedinto said induction chamber.

16. A process for the conveyance of granular solids which comprisesestablishing a surge zone, first and. second pressuring zonescommunicating therewith, said pressuring zones communicating with aninduction Zone opening into a conveyance zone, introducing solids to beconveyed into said surge zone, maintaining a relatively low pressure insaid surge Zone, maintaining a relatively high pressure in saidinduction Zone, depressuring said first pressuring zone to saidrelatively low pressure while maintaining said second pressuring zone atsaid relatively high pressure, flowing granular solids as a moving bedfrom said surge Zone into said first pressuring Zone, flowing granularsolids as a moving bed from said second pressuring zone into saidinduction zone, subsequently depressuring said second pressuring zoneand pressuring said first pressuring zone to said relatively lowpressures and relatively high pressure respectively, flowing granularsolids as a moving bed from said surge zone into said second pressuringzone, fiowing granular solids as a moving bed from said rst pressuringZone into said induction Zone, alternately pressuring and depressuringsaid pres` suring Zones to convey a relatively uniform fiow of granularsolids into said induction zone, introducing a conveyance fluid intosaid induction zone, depressuring said conveyance fiuid through saidconveyance zone ccncnrrently with a substantially constant flow ofcompact nonfluidized granular' solids, and applying a restrictive forceagainst solids discharging from said conveyance Zone thereby maintainingsaid granular solids therein in substantially compact nonfiuidized format a bulk density substantially the same as that of said moving beds.

17. A process according to claim 16 wherein a substantially constantflow of granular solids is maintained into said surge zone and granularsolids are intermittently removed therefrom alternately into said firstand second pressuring zones.

18. A process according to claim 16 wherein one of said pressuringvessels at a relatively high pressure is depressured by dischargingfluid into the other of said pressuring vessels at a relatively lowpressure bringing the two to an intermediate pressure, subsequentlydepressuring the one of said pressuring zones to said relatively lowpressure while pressuring the other of said pressuring vessels to saidrelatively high pressure.

19. A process according to claim 16 in combination with the step ofremoving a portieri of said conveyance iiuid at an intermediate pointalong said conveyance zone, compressing the thus removed fiuid, andreturning at least part thereof to said induction zone.

20. An apparatus which comprises a first and a second contacting chamberadapted to the contact of granular solids and fluids, conduit and valvemeans for passing solids from said first contacting zone successivelythrough a first surge zone, alternately into at least two firstpressuring chambers, and alternately therefrom into a first inductionchamber' as a relatively uniform fiow thereinto, an inlet conduit forconveyance fluid into said first induction chamber, a first conveyanceconduit communicating said first induction chamber with a secondseparator chamber, means for depressuring said conveyance fluidtherethrough, means for maintaining solids during conveyancetherethrough in substantially compact form, a conduit for solidscommunicating said second separator chamber with said second contactingchamber, an outlet conduit from said second separator chamber forconveyance Huid, conduit and valve means for passing solids therefromsuccessively through a second surge chamber, alternately into at leasttwo second pressuring chambers and alternately therefrom into secondinduction chamber as a relatively uniform flow thereinto, an inletconduit for conveyance `tiuid into said second induction chamber,

a second conveyance conduit communicating said second induction chamberwith a rst separator chamber, means for depressuring said conveyancefluid therethrough, means for maintaining solids during conveyancetherethrough in substantially compact form, a conduit for solidscommunicating said first separator chamber with said first contactingchamber, an outlet conduit from said first separator chamber forconveyance fluid, outlet conduits from an intermediate point along thelength of said first and second conveyanceV conduit, communi- 13 catingwith a uid pressuring means and conduits therefrom for repressured tluidopening into said rst and second induction chambers.

21. An apparatus for the conveyance of granular solids which comprises asurge chamber opening into at least one pressuring chamber, saidpressuring chamber opening into an induction chamber, means formaintaining the pressure in said surge chamber at a relatively low andconstant pressure, means for maintaining said induction chamber at arelatively high and constant pressure, means for pressuring anddepressuring said pressuring chamber between the limits of saidrelatively low pressure and said relatively high pressure, means foriiowing granular solids from said surge chamber to said pressuringchamber when the latter is depressured, means for flowing granularsolids from said pressuring chamber to said induction chamber when theformer is pressured, means for introducing a conveyance iluid into saidinduction chamber at said relatively high pressure, an elongatedconveyance conduit communicating with said induction chamber, means fordepressuring said conveyance fluid through a substantially compactmoving mass of granular solids maintained in said conveyance conduit, aconveyance fluid disengaging chamber having a cross sectional areamaterially greater than that of said conveyance conduit maintained at apoint intermediate the ends of said conveyance conduit, a disengagingtray within said disengaging chamber, an outlet conduit for at leastpart of said conveyance iiuid from said disengaging chamber, means forcompressing the thus withdrawn conveyance fluid, and means for returningat least a portion of the thus compressed conveyance iluid to saidinduction chamber.

22. An apparatus for the conveyance of granular solids which comprises afirst and a second surge chamber, separate inlets for solids thereto, afirst and a second pressuring chamber communicating in solids-receivingrelation through a first pair of valved conduits with said rst andsecond surge chambers respectively, an induction chamber communicatingin solids-receiving relation through a second pair of valved conduitswith said iirst and second pressuring chambers respectively, means formaintaining said surge chambers at a relatively low pressure, means formaintaining said induction chamber at a relatively high pressure byintroduction of a conveyance iiuid thereinto, means for pressuring anddepressuring said pressuring chambers between said relatively high andlow pressures as limits by introduction and removal of fluids, means foropening and closing said valved conduits in sequence to flow solids intosaid pressuring chambers when at said relatively low pressure and fromsaid pressuring chamber when at said relatively high pressure, anelongated conveyance conduit in solids-reeeiving relation at its inletwith said induction chamber, means for maintaining the outlet of saidconveyance conduit at a relatively low pressure to maintain ilow of saidconveyance uid and solids therethrough, and means for applying a forceagainst the solids discharging therefrom to maintain the moving solidstherein at a bullf density substantially equal to that of a downwardlymoving confined solids bed.

23. An apparatus according to claim 22 in combination with a valvedconduit communicating said first and second pressuring chambers wherebyupon opening the valve therein one chamber may be partially depre' suredby partially pressuring the other.

24. An apparatus according to claim 22 in combination with uiddisengaging means intermediate the ends of said elongated conveyanceconduit for disengaging fluid from moving solids therein, a fluidcompression means in Huid-receiving relation to said disengaging means,and a conduit for repressured iluid communicating said compression meanswith said induction chamber.

25. An apparatus for the conveyance of granular solids which comprises asolids surge chamber, an inlet conduit for solids opening thereinto, aiirst and second pressuring chamber each communicating insolids-receiving relation through a valved conduit with said surgechamber, an induction chamber communicating in solids-receiving relationthrough a pair of valved conduits with said pressuring chambers, meansfor maintaining said surge chamber at a relatively low pressure, meansfor maintaining said induction chamber at a relatively high pressure byintroduction of a conveyance iluid thereinto, means for pressuring anddepressuring said pressuring chambers between said relatively high andlow pressures as limits by introduction and removal of uids, means foropening and closing said valved conduits in sequence to How solids intosaid pressuring chambers when at said relatively low pressure and fromsaid pressuring chamber when at said relatively high pressure, anelongated conveyance conduit in solids-receiving relation at its inletwith said induction chamber, means for maintaining the outlet of saidconveyance conduit at a relatively low pressure to maintain flow of saidconveyance uid and solids therethrough, and means for applying a forceagainst the solids discharging therefrom to maintain the moving solidstherein at a bulk density substantially equal to that of a downwardlymoving coniined solids bed.

26. In an apparatus for the conveyance of granular solids whichcomprises an elongated conveyance conduit, means for submerging theinlet thereof with a bed of solids to be conveyed, means fordepressuring a conveyance fluid therethrough to convey said solids, andmeans for applying a force against solids discharging therefrom tomaintain the solids moving through said conveyance conduit atsubstantially the same bulk density as that of a confined downwardlymoving solids bed, the improved means for disengaging a portion of saidconveyance uid from said solids and removing it from said conduit at anintermediate point along the length thereof which comprises a conveyanceuid disengaging charnber having a materially greater cross-sectionalarea than that of said conveyance conduit and communicating insolids-receiving relation at its upper end with the first part of saidconveyance conduit and communicating in solids-delivery relation at itslower end with the second part of said conveyance conduit and adapted toconfine a downwardly moving bed of solids therein, a transverse traydisposed within said disengaging chamber below the solids inlet thereto,a plurality of open-ended tubes depending therefrom and through whichsaid bed of solids passes forming a solids-free disengaging space aroundsaid tubes and below said tray, and a valved outlet conduit for fluidopening from said disengaging chamber at a point immediately below saidtray.

27. An apparatus according to claim 26 wherein said disengaging chamberis provided with a conical upper portion and a conical lower portion,said transverse tray being disposed substantially at the coincidentbases of said conical portions.

References Cited in the file of this patent UNITED STATES PATENTS2,077,898 Rolf Apr. 20, 1937 2,331,433 Simpson et al. Oct. l2, 19432,435,158 Read `lan. 27, 1948 2,493,911 Brandt Jan. 10, 1950 2,509,983Morrow May 30, i950 2,541,077 Leiter Feb. 13, 1951 2,546,625 Bergstroma- Mar. 27, 1951 2,561,771 Ardern July 24, 1951 FOREIGN PATENTS 180,397Great Britain May 11, 1922 484,325 Germany n Apr. 30, 1927 OTHERREFERENCES Development of Houdriow Catalytic Cracking, Bland et al.,Houdry Pioneer, vol. 5, No. l, Feb. 1950, pages 5 to 7.

1. A PROCESS FOR RECIRCULATING GRANULAR SOLIDS SUCCESSIVELY THROUGH A FIRST AND A SECOND FLUID CONTACTING ZONE WHICH COMPRISES PASSING GRANULAR SOLIDS FROM SAID FIRST CONTACTING ZONE SUCCESSIVELY THROUGH A FIRST SURGE ZONE, ALTERNATELY INTO A PLURALITY OF FIRST PRESSURING ZONES, INTRODUCING A RELATIVELY UNIFORM FLOW OF GRANULAR SOLIDS FROM SAID PLURALITY OF PRESSURING ZONES INTO A FIRST INDUCTION ZONE, INTRODUCING A CONVEYANCE FLUID INTO SAID INDUCTION ZONE, DEPRESSURING SAID CONVEYANCE FLUID CONCURRENTLY WITH SAID GRANULAR SOLIDS FROM SAID FIRST INDUCTION ZONE THROUGH A FIRST CONVEYANCE ZONE TO A SECOND SEPARATOR ZONE, MAINTAINING SAID GRANULAR SOLIDS IN SAID CONVEYANCE ZONE IN SUBSTANTIALLY COMPACT FORM, FLOWING SAID GRANULAR SOLIDS FROM SAID SECOND SEPARATOR ZONE INTO SAID SECOND CONTACTING ZONE, FLOWING GRANULAR SOLIDS FROM SAID SECOND CONTACTING ZONE SUCCESSIVELY THROUGH A SECOND SURGE ZONE AND ALTERNATELY INTO A PLURALITY OF SECOND PRESSURING ZONES, PASSING SAID SOLIDS FROM SAID PRESSURING ZONES INTO A SECOND INDUCTION ZONE, DEPRESSURING SAID CONVEYANCE SAID SECOND INDUCTION ZONE, DEPRESSURING SAID CONVEYANCE FLUID FROM SAID SECOND INDUCTION ZONE THROUGH A SECOND CONVEYANCE ZONE INTO A FIRST SEPARATOR ZONE, MAINTAINING SAID GRANULAR SOLIDS IN SAID SECOND CONVEYANCE ZONE IN SUBSTANTIALLY COMPACT FORM AND AS A CONTINUOUSLY MOVING MASS, FLOWING GRANULAR SOLIDS FROM SAID FIRST SEPARATOR ZONE, INTO SAID FIRST CONTACTING ZONE, WITHDRAWING AT LEAST A PORTION OF SAID CONVEYANCE FLUID FROM EACH OF SAID FIRST AND SECOND CONVEYANCE ZONES AT AN INTERMEDIATE POINT THEREIN, COMBINING THE FLUID THUS FORMED, REPRESSURING SAID FLUID, AND INTRODUCING AT LEAST A PORTION THEREOF INTO SAID FIRST AND SECOND INDUCTION ZONES.
 3. A PROCESS ACCORDING TO CLAIM 1 WHEREIN SAID FIRST CONTACTING ZONE COMPRISES TWO ELONGATED REACTION ZONES, WHEREIN SAID GRANULAR SOLIDS COMPRISE A SOLID GRANULAR CRACKING CATALYST, WHEREIN SAID SECOND CONTACTING ZONE COMPRISES A CATALYST REGENERATION ZONE, INTRODUCING A SEPARATE STREAM OF REGENERATED GRANULAR CATALYST INTO EACH OF SAID REACTION ZONES, CONVEYING BY MEANS OF SAID FIRST CONVEYANCE ZONE A STREAM OF SPENT HYDROCARBONACEOUS CRACKING CATALYST INTO SAID REGENERATION ZONE, REGENERATING SAID SPENT CATALYST IN SAID REGENERATION ZONE BY CONTACTING THE SAME WITH AN OXYGEN-CONTAINING GAS FORMING A REGENERATED CATALYST, CONVEYING SAID REGENERATED CATALYST BY MEANS OF SAID SECOND CONVEYANCE ZONE TO SAID FIRST SEPARATOR ZONE, MAINTAINING SAID REGENERATED CRACKING CATALYST AT CRACKING CONDITIONS OF PRESSURE AND TEMPERATURE WITHIN SAID REACTION ZONE, AND CONTACTING SAID CATALYST THEREIN WITH A HYDROCARBON OIL TO BE CRACKED. 